Residual correction + status

Tome Anticic

NA61 collaboration week Oct 2011

Example: MTPC sector subdivision

anticic@irb.hr 2/10

YX

Z: 78 cm, 18 bins (4.3 cm each)

Y: 110 cm, 15 bins (7.46 cm each)

X: 70 cm, 9 bins 1 cm each

7 bins 7.3 cm each9 bins 1 cm each

6750 bins,Each direction, and sector separately

proper track residual minimization

anticic@irb.hr 3/10

Alignment procedure

Detector offsets and angles

Detailed residual corrections ( ExB etc)

Detector offsets agian

Detailed residual corrections ( ExB etc)

Generally, only this gets changed for different run configurations, after the

offset determination

Status overview

Scripts written so that now a new data set takes about 2 days of running, unless problems crop up (but these are now instructive problems, such as

drift v problems)

Corrections are now placed in format for database, but didn’t yet fully check it.

Code is added to program to also include GTPC geometry, but not residual corrections. Probably no need for residual corrections. Again, this is written,

but did not yet fully test it – no problem expected.

How useful?

anticic@irb.hr 5/10

Black: no residual

correction

Red:With

residual correctionBx

By

All tracks

Det id = 12(VT2+MTPCL)

Example: pp 158

How usefull II?

anticic@irb.hr 6/11

V1 X

V1 Y

ML X

ML Y

MR X

MR Y

V2 X

V2 Y

Example: pp 158

Some offset problems, require new geometry, apparent for different

types of tracks

Y residuals in MTPCL for different iddet before and after new offsets

anticic@irb.hr 7/10

Iddet 10 (V1+MTPCL)

Iddet 14(V1+V2+MTPCL)

Iddet 12(V2+MTPCL)

BEFORE

AFTER

Y Residuals vs row of MTPCL

Y Residuals vs row of MTPCL

Example: pp 158

Comparison with Monte Carlo bx and by all tracks 8712 (pc 31 GeV 2 cm)

anticic@irb.hr 8/10

BX

BY

8712

MC

Monte Carlo slightly betterAlso, not shown, y residuals vs row around zero

Residual x, y 8712, MC

anticic@irb.hr 9/11anticic@irb.hr 9/11

V1 X

V1 Y

ML X

ML Y

MR X

MR Y

V2 X

V2 Y

20 k events runs 8712

20 k events runs MC

Monte Carlo slightly better

VDRIFT problems: pp 31 GeV X and Y residuals, after residual corrections

anticic@irb.hr 10/11

V1 X

V1 Y

ML X

ML Y

MR X

MR Y

V2 X

V2 Y

20 k events runs 9004

20 k events runs 9043

Same residual corrections, same data set, different results – Vdrift

problem

Vdrift problem became apparent when differential residuals for VTs do not go to zero

anticic@irb.hr 11/11

BEFOREX

Y

AFTER

Comparison: pp 158 GeV before/after, VT2 2D

anticic@irb.hr 12/10

Before

X

Y

After

X

Y